System and method for deep vein thrombosis prevention and diagnosis

ABSTRACT

A system and method prevents and diagnoses deep vein thrombosis in a body limb by providing a pressure sleeve having a plurality of individually fillable cells, the pressure sleeve being configurable to be placed around a body limb. A source fills each fillable cell individually, and a pressure sensor measures a pressure in a fillable cell. A controller establishes a fill sequence of each individually fillable cell and a fill time for each individually fillable cell. The controller causes a first individually fillable cell of the pressure sleeve to be filled to a predetermined pressure and causes the pressure of first individually fillable cell of the pressure sleeve to be measured while a second individually fillable cell of the pressure sleeve is filled. The controller determines a presence of deep vein thrombosis in a body limb having the pressure sleeve therearound based upon a measured pressure change in the first individually fillable cell of the pressure sleeve. The monitored pressure changes reflects the effect of venous obstruction on naturally occurred venous flow fluctuations like those caused by the respiratory cycle, and/or artificially created fluctuations like those caused by inflation of a second pressure cell. Relevant data can be collected during routine system application for deep vein thrombosis prevention on a 24/7 basis. In the case deep vein thrombosis is suspected, a controlled and more sophisticated study can be triggered using the same system.

PRIORITY INFORMATION

This application claims priority from U.S. Provisional PatentApplication, Ser. No. 60/863,052, filed on Oct. 26, 2006. The entirecontent of U.S. Provisional Patent Application, 60/863,052, filed onOct. 26, 2006, is hereby incorporated by reference.

BACKGROUND

Deep vein thrombosis is of extreme clinical importance as it carries theshort-term risk of pulmonary embolism and death and the long term riskof chronic venous insufficiency, causing disabling symptoms of swelling,chronic pain, and skin ulceration (post thrombotic syndrome). Bothpulmonary embolism and post-thrombotic syndrome may develop aftersymptomatic or asymptomatic, proximal or distal deep vein thrombosisevents. Prevention of these short-term and long-term sequelae is ofgreat clinical, economic, medical, and legal significance.

Due to the silent nature of deep vein thrombosis and pulmonary embolism,prevention has been the conventional clinical approach to avoid thisdisease. More specifically, prevention protocols have beenconventionally used with any high-risk patients and especially withsurgical patients. Conventional prevention therapies include eitherchemoprophylaxis (anticoagulant drugs) or mechanical (systems thatenhance the venous return by compressing the legs).

Despite great progress with these two modalities of prevention in therecent years, conventional prevention therapies pose a high failure rateand a significant risk to surgical patients. Meta analysis studiesshowed that failure rate of the most common anticoagulant drug, LMWH, isabout 16% in patients under going total hip replacement and 31% withpatient undergoing total knee replacement. Given such a high failurerate there is a great need for routine screening to role out DVT in highrisk patients. The conventional prevention therapies do not address theneed to detect deep vein thrombosis in patients in which the prophylaxishas failed. More specifically, deep vein thrombosis screening is,conventionally, only done with patients who are suffering from clinicalsymptoms, and only 5% of the deep vein thrombosis patients have clinicalmanifestation.

Deep vein thrombosis can be conventionally diagnosed using venography,an invasive and relatively high-risk method, or a duplex scan. Bothconventional diagnostic methods are expensive and can be done only inthe hospital settings by a skilled technician. Thus, routine scanningfor deep vein thrombosis with either duplex or venography is not costeffective; and therefore, scanning is not conventionally used.

Conventionally, once clinical symptoms are present (only about 5% of thedeep vein thrombosis patients show clinical signs during the first 3-5post operation days), a patient will go through a duplex scan to confirmor rule out the presence of deep vein thrombosis to allow for adequatetreatment to be taken, There are two major down sides to thisconventional approach.

The first problem is as the scan can only be made in the hospitalssettings, the scans are done relatively a short time after theoperation, usually just before discharge (3-5 days after the operation).However, many of the deep vein thrombosis situations are either toosmall to be detected at this time or even start manifestation later.

The second problem is that the current available scans are a one time“snap shot” of the patient's situation and cannot provide anunderstanding with respect to earlier or later situations. Therefore, apositive scan can often time detect a fully developed clot that couldhave been controlled if it was discovered earlier. Alternatively, anegative scan could miss a small clot that is about to develop, postdischarge, into a significant clot.

With respect to the use of the anticoagulant drugs, anticoagulant drugsexpose the patient to the serious risk of bleeding complications. Forexample, it is known that 2%-5% of the patients using the anticoagulantdrug, LMWH, for deep vein thrombosis prevention in joint arthroplastiesexperience serious bleeding complications.

In view of this serious side effect, since only about 50% of thepatients who are at risk for developing deep vein thrombosis actuallydevelop deep vein thrombosis, more than half of the at-risk patients aresubjected to a totally unnecessary risk of bleeding due to theconventional widespread use of anticoagulant drugs to prevent deep veinthrombosis.

Furthermore, as the conventional prophylaxis protocols are extendedbeyond the acute care time (10-30 days with joints arthroplastypatients), patients are being discharge with the risk of developing deepvein thrombosis due to prevention failure, of bleeding complications dueto the continued use of anticoagulant drugs beyond the acute care time,or of both developing deep vein thrombosis and bleeding complications.It is noted that once the patient has detected a post acute care timeproblem and seeks clinical treatment, the situation is usually veryserious or too late.

Therefore, it is desirable to provide a device that will detect, in realtime and on a 24/7 basis, the possible formation of deep vein thrombosisin patients in acute care and/or post acute settings. Furthermore, it isdesirable to provide a device that will be able to prevent deep veinthrombosis, in real time and on a 24/7 basis, as well as detect thepossible formation of deep vein thrombosis. Moreover, it is desirable toprovide a device that will provide deep vein thrombosis screening forpatients receiving mechanical prophylaxis without any additionalhardware.

Also, it is desirable to provide a device that will be able to reducethe rates of symptomatic deep vein thrombosis and pulmonary embolism byalerting the presence of an early formation of deep vein thrombosis andtriggering early initiation of treatment. It is desirable to provide adevice that can eliminate the risk of unnecessary bleeding associatedwith the wide use of anticoagulant by providing good prophylaxiscapabilities together with good diagnostic capabilities in case ofprophylaxis failure that together will eliminate the need to useanticoagulant drugs for the same purpose. It is further desirable toprovide a device that will be able to protect against and detect deepvein thrombosis when the patient is out of the hospital.

In addition, it is desirable to provide a device that will be able toprovide information on the progress of the condition and its acutenessor healing instead of providing a snapshot of the situation.Furthermore, it is desirable to provide a device that is capable offollowing dynamic trends that have been developed along treatment timeaxis and incorporate such dynamic trends into the decision-makingalgorithm.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are only for purposes of illustrating embodiments and arenot to be construed as limiting, wherein:

FIG. 1 is an illustration showing an exemplary embodiment of amassage/diagnostic sleeve in use on the leg of a patient;

FIG. 2 is a schematic block diagram of an exemplary embodiment of a pumpunit;

FIG. 3 graphically illustrate relationships between femoral venous flowand respiration; and

FIGS. 4 through 7 illustrate an example of valves' states that enablealternate use of the pressure massage/diagnostic sleeve's air-cells asrecording cuffs or compression sites.

DETAILED DESCRIPTION

For a general understanding, reference is made to the drawings, In thedrawings, like reference have been used throughout to designateidentical or equivalent elements. It is also noted that the variousdrawings may not have been drawn to scale and that certain regions mayhave been purposely drawn disproportionately so that the features andconcepts could be properly illustrated.

In the following descriptions, the concepts will be described withrespect to use on a leg of an individual. However, it is to beunderstood that the concepts are also extended to use on any body limbsuch as an arm, a foot, a part of a leg, arm, or foot, and may be usedon two or more limbs simultaneously.

Moreover, although the concepts will be described in conjunction with aportable pneumatic compression system console or small pneumaticcompression system console wherein the medium used to providecompression is realized by pressurized air, the concepts can be usedwith any compression system wherein the medium used to providecompression can be realized by a liquid, fluid, gas, or any othermechanical means,

The descriptions below relate to medical devices for applying pressureto a region of a body surface. More particularly, the descriptions belowrelate to medical devices that use a pressure sleeve to apply pressureto a region of a body surface for deep vein thrombosis therapeutic anddiagnostic purposes.

Moreover, the descriptions below relate to systems for applyingcompressive pressures against a patient's limb, as well as, measuringvenous phasic signals to enable the detection of deep vein thrombosiswherein a miniaturized, portable, ambulant, massage/diagnostic systemmay be utilized,

It is noted that the entire contents of U.S. patent application Ser.Nos. 11/023,894 and 10/370,283 are hereby incorporated by reference. Theentire content of U.S. Pat. No. 7,063,676 is hereby incorporated byreference,

In FIG. 1, an exemplary embodiment of a pressure massage/diagnosticsleeve 1 is illustrated. The pressure massage/diagnostic sleeve 1 has aninner and outer surface composed of a durable flexible material and isdivided into a plurality of cells 2 along its length arid each cell isconnected to the control unit 3 by a separate tube collectively labeled4 in FIG. 1. Sections of the pressure massage/diagnostic sleeve may beof non-inflatable elastic material 5, for example around the knee andankle.

As illustrated in FIG. 1, each cell has a fluid inlet opening 6 to whicha hose 4 from the control unit 3 is attached. The control unit 3contains a compressor capable of compressing and pumping ambient airinto one or more selected cells in the pressure massage/diagnosticsleeve via the hoses 4. It is noted that the console may also include acompression system wherein the medium used to provide compression can berealized by a liquid, fluid, gas, or other mechanical means.

The control unit 3 allows a temporo-spatial regime of inflation anddeflation of the cells to be selected, e.g. a regime which generatesperistaltic contractions of the pressure massage/diagnostic sleeve so asto force fluids inside the limb towards the proximal end of the limb, ora regime which enhances the flow of the venous blood in the limb.

The cells may be subdivided into a plurality of intra-cell compartments7. The intra-cell compartments 7 are formed, for example, by welding theinner and outer shells of the pressure massage/diagnostic sleeve alongthe boundaries of the intra-cell compartments. The intra-cellcompartments 7 in a given cell are confluent due to openings 8 betweenadjacent intra-cell compartments 7 so that all the intra-cellcompartments 7 in the cell are inflated or deflated essentiallysimultaneously.

FIG. 2 is a schematic block diagram of a pump unit 60. It will beappreciated that the thick interconnecting lines represent a pneumaticconnection or multiple pneumatic connections, while the thininterconnecting lines represent an electrical connection or multipleelectrical connections. The pump unit 60 may include an independentsource of energy, such as a rechargeable battery pack 67, which enablesthe pneumatic device operation without a fixed connection to a mainpower outlet. The batteries can be bypassed and the device is able tooperate for longer times. and the batteries can be recharged at the sametime, while it is connected to the main power supply with the aid of acharger.

A source of compressed air, such as a compressor 64, is powered by thebatteries or the main electrical outlet, and connected to the pressuremassage/diagnostic sleeve or sleeves by pneumatic conduits. A controlunit 68 is adapted to receive inputs from the operator and from pressuresensors 62 and 63.

The control unit serves to read and control the operation of thecompressor 64 and to control the cyclic inflating and deflating of thepressure massage/diagnostic sleeve. The control unit also controls theoperation of solenoid valves 66, which receive and distribute the flowto the different cells of the pressure massage/diagnostic sleeve withthe aid of a manifold 65, to enable the sequential inflating anddeflating of the multi-segmented pressure massage/diagnostic sleeve'scells.

It is noted that the compressor 64 may be housed with the control unitor may be housed separately. It is noted that pressure sensors 62 and 63may have individual pneumatic connections with the manifold 65.

Alternatively, both the hardware and software can enable the operationof the device from an external pressurized air and power sources. Insome hospitals, the source of pressurized air can be the central sourceof pressure-regulated supply that has wall outlets adjacent to the poweroutlets or that both the external power and pump sources could be anintegral part of the patient's bed.

The use of miniaturized components like the compressor 64 and solenoidvalves 66, together with the miniature accessories, results in smallpower consumption that enables the operation of the pneumatic device onbatteries, while maintaining small dimensions and lightweight of theoperating unit. The use of a pressure massage/diagnostic sleeve with asmall-inflated volume can also improve the obtained results of theoperation unit for better clinical operation and results.

The system applies cyclic sequential pressure on a body's legs or arms.The cyclic sequential pressure is applied on the treated parts of thebody by inflating and deflating each cell of the pressuremassage/diagnostic sleeve at a predefined timing. While being inflated,the multi-chambered segmented sleeve should be encircling the part ofleg to be treated. While the pressure massage/diagnostic sleeve isinflated, a local pressure is applied at the contact area between thepressure massage/diagnostic sleeve and the body.

The control unit 68, which can be software based, controls the operationof the compressor 64 and solenoid valves 66. The control unit can beprogrammed to achieve any desired inflating, deflating, and/or recordingsequence and timing including delay intervals, in accordance withclinical application.

As noted above, deep vein thrombosis can be detected using a noninvasiveand painless technique that enables the detection of acute deep veinthrombosis, gives some basic idea on the location of the pathologicallesion (proximal/distal), and differentiates acute deep vein thrombosisfrom chronic deep vein thrombosis. The technique measures two variables.The first is the presence or absence of obstruction in the deep venoussystem. The second is a measurement of the collateral venouscirculation. These variables are indicated by the presence, absence, orsize and configuration of the naturally occurred, venous phasic flowwaves (the “venous phasic signal”). In other words, it requiresknowledge of the state of the venous phasic signals when it isdetermining the presence or absence of an obstruction.

If there is an obstruction without venous phasic waves, the process isacute. A sub-acute process is indicated by the presence of obstructionwith visible venous phasic waves. If there is evidence of obstruction inthe presence of larger than normal venous phasic waves, the process isusually chronic.

The volume of the lower limb is directly affected by respiration,Respiration has a neglect effect on the limb arterial flow at rest;however, during inspiration (in diaphragmatic respiration) there is atemporary reduction in limb venous return, which temporarily increasesthe total volume of the leg. Expiration has the opposite effect. This isillustrated in FIG. 3.

FIG. 3 demonstrates the average effects of ribcage or diaphragmbreathing patterns on femoral arterial inflow, mean arterial pressure,and femoral venous outflow. Signals were recorded during restingconditions in five healthy volunteers. A minimum of 200 breaths wererecorded per subject per condition, Though there is no discernableeffect of the breathing pattern on arterial inflow, femoral venousreturn is facilitated during ribcage inspiration and impeded during adiaphragmatic inspiration, with these modulatory effects being reversedduring the ensuing expiratory phase of the breath.

As noted above, the knowledge of the state of the venous phasic flow isrequired when it is determining the presence or absence of anobstruction. The fact that respiration has direct affect on leg volumemeans that by following periodic changes in leg volume one can determinethe state of the venous phasic flow. The present invention employs one(or more) of inflatable cells of a massage/diagnostic pressure sleeve asa recording cuff to measure an increase or decrease in the volume of thelumen (limb or body part within the inflatable cell) of the inflatablecell. The increase or decrease in the volume of the lumen will produce asimilar change in the pressure of the captive air, which change can berecorded with a suitable transducer (pressure sensor).

To better understand how the present invention diagnoses deep veinthrombosis of the lower extremity the characteristics of deep veinthrombosis of the lower extremity with respect to blood flow will bedescribed.

It is known that normal breathing produces a rhythmic increase anddecrease in the volume of blood in the lower extremity of a normalpatient, These changes (venous phasic waves) are usually larger inamplitude when the patient lies on his left side than those obtainedwhen the patient is supine. It is further known that acute deep venousthrombosis obliterates or significantly reduces the size of the “venousphasic waves” in veins distal to the obstruction.

It is noted that deep venous thrombosis interferes with the normaloutflow of blood from the lower extremities wherein the outflow of bloodfrom the lower extremities is in response to rhythmic compression. If arecording cuff is placed proximal (higher or closer to the heart thanthe site of compression is to the heart) to the site of compression anda rise in the baseline of the volume recorder, attached to the recordingcuff, takes place, it can be determined that a venous obstruction isproximal to the recording cuff. For example, if the thigh tracing showsa stepwise rise while the calf is being compressed, the level ofobstruction to the deep veins is located above the thigh cuff. In thisscenario, the recording cuff is detecting a momentary damming up ofblood (increase in blood volume) due to deep vein thrombosis blockingthe blood's from exiting the area; e.g., indicative of a blockage.

However, when a recording cuff is placed proximal to the site ofcompression and the baseline of the volume recorder, attached to therecording cuff, remains level, it can be determined that compression hasbeen applied to a normal extremity having no impediment to venousoutflow.

On the other hand, if a recording cuff is placed distal (lower orfurther from the heart than the site of compression is to the heart) tothe site of compression and a fall in baseline of the volume recorder,attached to the recording cuff, takes place, it can be determined thatcompression has been applied to a normal extremity having no impedimentto venous outflow.

Moreover, if a recording cuff is placed distal to the site ofcompression and no changes or very small changes in baseline of thevolume recorder, attached to the recording cuff, takes place, it can bedetermined that deep vein thrombosis is located proximal to thecompression site.

It is further noted that monitoring changes in the amplitude of thevenous phasic waves over time can help identify deep vein thrombosisformation at an early stage. A trend towards an amplitude reduction inone leg as compared to the other leg, which remains unchanged, mayindicate an on-going deep vein thrombosis process in the leg with thelower amplitude. A trend towards an increase in venous phasic waveamplitude in one leg as compared to the other leg, which remainsunchanged, may indicate chronic deep vein thrombosis withre-canalization.

FIGS. 4-7 illustrate an example of valves' states that enable alternateuse of the pressure massage/diagnostic sleeve's air-cells as recordingcuffs or compression sites. As illustrated in FIG. 4, a programmableconsole system is configured to illustrate a method of detecting deepvein thrombosis using a pressure massage/diagnostic sleeve (not shown)comprising two or more individually inflatable cells.

The system also includes a console 6150 containing a compressor 6020that generates pressurized air. A conduit 6070 conducts the flow ofpressurized air away from the compressor 6020. The console 6150 has ahousing 6200 containing a processor 6190, conduit 6070 and valves (6050a, 6050 b, and 6050 c). The compressor 6020 may be located within thehousing 6200 of the console 6150 or outside the housing of the console6150.

The number of solenoid valves (6050 a, 6050 b, and 6050 c) can he equalto the number of cells in the pressure massage/diagnostic sleeve and arepositioned along the conduit 6070. Each valve (6050 a, 6050 b, and 6050c) has an air inlet connected to an upstream portion of the conduit6070, a first air outlet connected to a downstream portion of theconduit 6070, a second air outlet (6110 a, 6110 b, and 6110 c) connectedto an associated cell via a conduit (6140 a, 6140 b, and 6140 c), and athird air outlet connected to conduit 6075. A one--way valve 6250prevents the flow of air in the conduit 6070 from flowing from thevalves (6050 a, 6050 b, and 6050 c) towards the compressor 6020. Eachvalve can, individually, realize various states. The state of each valveis controlled by control signals from a processor 6190.

In a first state, a valve allows pressurized air to flow between itsinlet and the first outlet. In a second state, a valve allowspressurized air to flow between its inlet and the first outlet and thesecond outlet (6110 a, 6110 b, or 6110 c). In a third state, a valveallows pressurized air to flow between the second outlet (6110 a, 6110b, and 6110 c) and the third outlet connected to conduit 6075, In afourth state, a valve allows the pressurized air in the pressuremassage/diagnostic sleeve, conduit 6070, and conduit 6075 to beexhausted from the system.

As noted above, the processor 6190 controls the state of each of thevalves (6050 a, 6050 b, and 6050 c) so as to execute a predeterminedtemporo-spatial array of inflation/deflation of the cells. For example,in the application of detecting deep vein thrombosis, the cells areinflated individually so that one cell can act as a recording cuff,while another cell can act as a compression site.

As illustrated in FIG. 4, this can be accomplished by the processor 6190causing the valve 6050 c to realize the second state (pressurized airflowing between its inlet and the first outlet and the second outlet6110 c), while the valves 6050 a and 6050 b realize the first state(pressurized air flowing between its inlet and the first outlet).Pressurized air flows in the conduit 6070 from the compressor 6020 intothe cell associated with conduit 6140 c. The processor 6190 monitors theair pressure in the conduit 6070 by means of a pressure gauge 6030. Whenthe pressure has reached a predetermined pressure, the processor 6190closes the valves (6050 a, 6050 b, and 6050 c).

Next, as illustrated in FIG. 5, the cell associated with conduit 6140 ais inflated by causing the valve 6050 a to realize the second state(pressurized air flowing between its inlet and the first outlet and thesecond outlet 6110 a). The cell associated with conduit 6140 b is notinflated because valve 6050 b is closed. While the cell associated withconduit 6′140 a is being inflated, the cell associated with conduit 6140a is causing pressure (compression) to be applied to the limb, and thecell associated with conduit 6140 c, which was pre-inflated to apredetermined pressure, is pneumatically connected to pressure sensor6035 via valve 6050 c being in the third state. In this situation, thecell associated with conduit 6140 c is acting as a recording cuff, whichcommunicates lumen volume change via pressure changes that are detectedby the pressure sensor 6035.

The recording cuff (the cell associated with conduit 6140 c) is placedproximal to the site of compression (the cell associated with conduit6140 a). If the recording cuff, via the pressure sensor 6035, causes arise in the baseline of the volume recorder, it can be determined that avenous obstruction is proximal to the recording cuff (the cellassociated with conduit 6140 c). In this scenario, the recording cuff isdetecting a momentary damming up of blood (increase in blood volume) dueto deep vein thrombosis blocking the blood's from exiting the area;e.g., indicative of a blockage. However, if the recording cuff, via thepressure sensor 6035, causes the baseline of the volume recorder toremain level, it can be determined that compression has been applied toa normal extremity having no impediment to venous outflow.

As illustrated in FIG. 6, the processor 6190 causes the valve 6050 a torealize the second state (pressurized air flowing between its inlet andthe first outlet and the second outlet 6110 a), while the valves 6050 band 6050 c are closed. Pressurized air flows in the conduit 6070 fromthe compressor 6020 into the cell associated with conduit 6140 a. Theprocessor 6190 monitors the air pressure in the conduit 6070 by means ofa pressure gauge 6030. When the pressure has reached a predeterminedpressure, the processor 6190 closes the valves (6050 a, 6050 b, and 6050c).

Next, as illustrated in FIG. 7, the cell associated with conduit 6140 ais pneumatically connected to pressure sensor 6035 via valve 6050 abecause the processor 6190 causes the valve 6050 a is realize the thirdstate. While the cell associated with conduit 6140 b is being inflated,the cell associated with conduit 6140 b is causing pressure(compression) to be applied to the limb. In this situation, the cellassociated with conduit 6140 a is acting as a recording cuff, whichcommunicates lumen volume change via pressure changes that are detectedby the pressure sensor 6035.

The recording cuff (the cell associated with conduit 6140 a) is placeddistal to the site of compression (the cell associated with conduit 6140b). If the recording cuff, via the pressure sensor 6035, causes a fallin baseline of the volume recorder, it can be determined thatcompression has been applied to a normal extremity having no impedimentto venous outflow. However, if the recording cuff, via the pressuresensor 6035, causes no changes or very small changes in the baseline ofthe volume recorder, it can be determined that deep vein thrombosis islocated proximal to the compression site (the cell associated withconduit 6140 b).

It is noted that the change in the pressure in the cells can becontrolled by integrally controlling the states of valves. The change inpressure is determined by the mode of the programmable console.

For example, in some medical conditions it is beneficial to produce afast inflation of the sleeve encompassing the body surface because thevelocity of venous flow or the increase in local arterial flow isproportional to the rate at which the pressure rises. In the preventionof deep vein thrombosis, it is believed that this acceleration of venousflow reduces the risk of pooling and clotting of blood in the deep veinsand therefore the rate of pressure rise is a critical variable ofeffectiveness in the prevention of deep vein thrombosis.

In the examples discussed above, the massage/diagnostic compressionsleeve may be a calf sleeve having three air cells that encircle thelower, middle, and upper calf parts.

The compression sleeve may include an inflatable cell having at leasttwo intra-cell compartments. The intra-cell compartments are confluent,The inflatable cell may include inner and outer shells of durableflexible material, the inner and outer shells being bonded together toform a perimetric cell bond and being further bonded together alongcompartmental bonds, The perimetric cell bond includes upper and lowerperimetric cell bonds. The compartmental bonds partly extend between theupper and lower perimetric cell bonds to allow for confluent airflowbetween adjacent intra-cell compartments within the cell.

As noted above, the inflatable cell includes at least two intra-cellcompartments, the intra-cell compartments being confluent to allow forconfluent airflow between adjacent intra-cell compartments within thecell, Adjacent intra-cell compartments are spatially fixed relative toeach other such that upon inflation of the cell, the cell becomescircumferentially constricted. The inflatable cell has a firstcircumference when the intra-cell compartments are deflated and a secondcircumference when the intra-cell compartments are inflated. The secondcircumference is less than the first circumference so as to provide forcircumferential constriction. The second circumference may be defined asa circumference passing through center points of each contiguousinflated intra-cell compartment.

It is further noted that the inflatable cell has a first intra-cellcompartmental dimension value when the inflatable cell is deflated and asecond intra-cell compartmental dimension value when the inflatable cellis inflated, the second intra-cell compartmental dimension value beingless than the first intra-cell compartmental dimension value so as toprovide for circumferential constriction of the inflatable cell. Thefirst intra-cell compartmental dimension value may be a length betweenadjacent compartmental bonds when the inflatable cell is deflated. Thesecond intra-cell compartmental dimension value may be a length betweenthe adjacent compartmental bonds when the inflatable cell is inflated.

As explained above, the present invention controls the states of thevarious valves and the individually addressable air cells of amassage/diagnostic compression sleeve to sense small changes in limbvolume that relate to the venous phasic flow.

By allowing the individual air cells of the massage/diagnosticcompression sleeve to function alternately as “recording cuffs” and“compressing cuffs,” the present invention can function as a simplediagnostic system.

Furthermore, if the present invention is utilized on a 24/7 basis,convenient long-term follow-up and serial tracings can be realized. Thisautomatically collected information can be used to identify trends invenous phasic signals amplitude changes and limb volume changes.

In the case of proximal obstruction (deep vein thrombosis), the venousblood pool distal to the lesion increases with parallel increase in limbvolume. This increase in limb volume reduces the time needed for fullinflation of the activated air cell up to the target pressure.Accordingly, assuming that the pump flow, air cell volume, and targetpressure all remained the same, a trend towards decreased inflation timeis suggestive of venous and/or lymphatic obstruction.

In addition the present invention is capable of collecting and analyzingtrends in heart rate and respiratory rate at rest. Though not specific,a trend towards increasing respiratory rate at rest to >16/min and/orbeat rate at rest to >100/min are suggestive of a patient suffering fromacute pulmonary embolism.

It is noted that cross analysis, integrating all four trends, mayimprove the ability to correctly diagnose ongoing pathological process,the level of chronicity, and the extent of the disease. Moreover,manually entered clinical data (such as Wells score) can be integratedinto the decision-making algorithm to further increase the accuracy ofthe final diagnosis.

It is further noted that the information about venous phasic signalamplitude, cell inflation time, respiratory rate, and heart rate trendscan be collected simultaneously by the present invention when thepresent invention is in a standard “treatment mode.” The data can becollected while using single-cell sleeve or sleeve composed of pluralityof individually inflated cells. If the present invention is in a“diagnostic mode,” the full test can be done automatically, assumingthat the sleeve used is composed of at least two individually inflatablecells. In the case of a single cell sleeve, the diagnostic mode can beused separately on each of the involved limbs, using the contra laterallimb sleeve as the needed second inflatable cell.

The signal processing and the diagnostic decision-making can be doneusing the processor of the present invention, or alternatively, the rawdata can be communicated to an external processing device for finalprocessing.

To realize a test, a patient lies quietly in bed with the lowerextremities approximately 10 degrees below heart level. In this example,the massage/diagnostic compression sleeve encompasses the patient'scalf. As noted above, the present invention is in a “diagnostic mode.”In the diagnostic mode, the present invention may execute twooperational algorithms: algorithm A and algorithm B.

In algorithm A, an upper air cell records the response to compression ofthe lower calf caused by quick inflation of the lower air cell. Inalgorithm B, the upper and lower air cells are recording the response tocompression of the mid-calf caused by quick inflation of the middle aircell. Typically, the sensing cells are inflated to 15-20 mm Hg and thecompressing cell to 100 mm Hg with pump acceleration.

In one embodiment, each run may be repeated three times and each recordcycle may last 35 seconds. Inflation cycles may be activatedsequentially in both legs so that a full set of tests for both legs maytake about 7 minutes.

With respect to a normal patient, during algorithm A, good venous phasicwaves should be detected by the upper air cell, and lower calfcompression does not cause an increase in baseline pressure as detectedby the upper cell, Moreover, with respect to a normal patient, duringalgorithm B, good venous phasic waves should be detected by the upperand the lower air cells, and mid-calf compression causes good lower-calfemptying, which causes fall in baseline pressure as detected in thelower air cell and. The baseline at the upper air cell remainsunchanged.

With respect to a patient having acute proximal deep vein thrombosis,during algorithm A, there is an obliteration of venous phasic waves inthe upper-calf, as well as baseline elevation secondary to lower-calfcompression. Moreover, with respect to a patient having acute proximaldeep vein thrombosis, during algorithm B, there is an obliteration ofvenous phasic waves in the upper-calf, as well as baseline elevationsecondary to mid-calf compression. The lower air cell detects only minordecrease in baseline pressure, if at all, with no venous phasic waves.

With respect to a patient having acute distal (mid-calf) deep veinthrombosis, during algorithm A, there are good venous phasic waves inthe upper-calf, without baseline elevation secondary to lower-calfcompression. Moreover, with respect to a patient having acute distal(mid-calf) deep vein thrombosis, during algorithm B, there are goodvenous phasic waves in the upper calf and absence of venous phasic wavesin the lower calf. Compression of the mid-calf has only minor effects onbaseline pressures in both the upper and lower air cells.

With respect to a patient having post deep vein thrombosis syndrome(chronic obstruction with collateral circulation), during algorithm A,there are larger than normal venous phasic waves in the upper-calf, withbaseline elevation secondary to lower-calf compression. Moreover, withrespect to a patient having post deep vein thrombosis syndrome (chronicobstruction with collateral circulation), during algorithm B, there arelarger than normal venous phasic waves, as well as baseline elevationsecondary to mid-calf compression in the upper air cell. The lower aircell detects only minor decrease in baseline pressure, if at all, withlarger than normal venous phasic waves.

In summary, the described systems enable the addition of diagnosticcapabilities in addition to the compression therapy. Moreover, thedescribed systems can be utilized with other deep vein thrombosisdiagnostic approaches, Furthermore, the described systems are directedto a compression system for applying therapeutic pressure to a limb of abody and enabling diagnostic capabilities that includes a pressuresleeve; a compression system console, pneumatically connected to thepressure sleeve, having a controller and compressor to providecontrolled pressurized fluid to the pressure sleeve.

The compression console system may be portable, battery operated with arechargeable battery. The compression system may indicate an appropriateinflation and deflation sequence.

A system for diagnosing deep vein thrombosis in a body limb may includea compression system for applying external pressure to a body limb and avenous phasic flow monitoring system to monitor a venous phasic flow ina body limb. The venous phasic flow monitoring system determines apresence of deep vein thrombosis in the body limb by detecting a changein a volume of the body limb. The compression system may include apressure sleeve to apply external pressure to the body limb, thepressure sleeve having a fillable cell and being configurable to beplaced around a body limb. The compression system may further include asource to fill the fillable cell,

The source may pneumatically fill the fillable cell. The venous phasicflow monitoring system may determine a presence of deep vein thrombosisin the body limb having the pressure sleeve therearound based upondetecting a pressure change in the fillable cell. The pressure sleevemay include a plurality of individually fillable cells and the sourcefills each fillable cell individually. The source may fill a firstindividually fillable cell of the pressure sleeve to a predeterminedpressure. The source may fill a second individually fillable cell of thepressure sleeve while the venous phasic flow monitoring system monitorsa pressure change in the filled first individually fillable cell of thepressure sleeve. The venous phasic flow monitoring system may determinea presence of deep vein thrombosis in the body limb having the pressuresleeve therearound based upon detecting a pressure change in the filledfirst individually fillable cell of the pressure sleeve.

The first individually fillable cell of the pressure sleeve may beproximal to the second individually fillable cell of the pressuresleeve. The first individually fillable cell of the pressure sleeve maybe distal to the second individually fillable cell of the pressuresleeve.

The venous phasic flow monitoring system may determine a presence ofdeep vein thrombosis in a body limb having the pressure sleevetherearound based upon substantially no pressure change being measuredby the venous phasic flow monitoring system. The venous phasic flowmonitoring system may determine that the deep vein thrombosis is locatedin a body limb having the pressure sleeve therearound, distal to thesecond individually fillable cell, based upon substantially no pressurechange being measured by the venous phasic flow monitoring system. Thevenous phasic flow monitoring system may determine an absence of deepvein thrombosis in a body limb having the pressure sleeve therearoundbased upon a pressure decrease being measured by the pressure sensor.The venous phasic flow monitoring system may determine a presence ofdeep vein thrombosis in a body limb having the pressure sleevetherearound based upon a pressure increase being measured by the venousphasic flow monitoring system.

The venous phasic flow monitoring system may determine that the deepvein thrombosis is located in a body limb having the pressure sleevetherearound, proximal to the first individually fillable cell, basedupon a pressure increase being measured by the venous phasic flowmonitoring system. The venous phasic flow monitoring system maydetermine an absence of deep vein thrombosis in a body limb having thepressure sleeve therearound based upon substantially no pressure changebeing measured by the venous phasic flow monitoring system.

The compression system may change a fill time for one of the pluralityof individually fillable cells of the pressure sleeve based upon thedetermination of the presence of deep vein thrombosis in the body limbhaving the pressure sleeve therearound. The venous phasic flowmonitoring system may monitor a pressure in the fillable cell to createa history of pressure values. The venous phasic flow monitoring systemmay determine a presence of deep vein thrombosis in the body limb havingthe pressure sleeve therearound based upon the history of pressurevalues for the fillable cell. The venous phasic flow monitoring systemmay monitor a progression of a clot in the body limb having the pressuresleeve therearound based upon the history of pressure values for thefinable cell. The venous phasic flow monitoring system may monitor adissolving of a clot in the body limb having the pressure sleevetherearound based upon the history of pressure values for the fillablecell.

The compression system may apply external pressure to a second body limbusing a second pressure sleeve. The venous phasic flow monitoring systemmay monitor a venous phasic flow in the second body limb. The venousphasic flow monitoring system may determine a presence of deep veinthrombosis in the first body limb having the pressure sleeve therearoundbased upon comparing a detection of a pressure change in the fillablecell of the pressure sleeve around the first body limb and a detectionof a pressure change in the fillable cell of the second pressure sleevearound the second body limb.

The venous phasic flow monitoring system may detect cyclic pressurechanges within the fillable cell, the cyclic pressure changes being incorrelation with changes in the venous return of the body limb caused byrespiration. The venous phasic flow monitoring system may determine apresence of deep vein thrombosis based upon gradual deterioration ordisappearance of the cyclic pressure changes over a predetermined periodof time.

A system for diagnosing and treating deep vein thrombosis in a body limbmay include a compression system for applying external pressure to abody limb and a venous phasic flow monitoring system to monitor a venousphasic flow in a body limb. The venous phasic flow monitoring system maydetermine a presence of deep vein thrombosis in the body limb bydetecting a change in a volume of the body limb. The compression systemmay change a characteristic of an application of external pressure tothe body limb based upon the presence of deep vein thrombosis in thebody limb.

A method for diagnosing deep vein thrombosis in a body limb may applyexternal pressure to a body limb; monitor a venous phasic flow in a bodylimb; and determine a presence of deep vein thrombosis in the body limbby detecting a change in a volume of the body limb. Furthermore, amethod for diagnosing and treating deep vein thrombosis in a body limbmay apply external pressure to a body limb; monitor a venous phasic flowin a body limb; determine a presence of deep vein thrombosis in the bodylimb by detecting a change in a volume of the body limb; and change acharacteristic of an application of external pressure to the body limbbased upon the presence of deep vein thrombosis in the body limb.

These various embodiments enable the online 24/7 monitoring of theprogression of deep vein thrombosis (creation or dissolving of deep veinthrombosis) with the same device that is used online 24/7 for theprevention of deep vein thrombosis. More specifically, the variousembodiments utilize an online 24/7 monitoring of the venous phasic flowby detecting small pressure changes in one cell to determine deep veinthrombosis. The pressure changes are indicative of the venous phasicflow.

Although the various embodiments have been described in conjunction withpneumatic pressure (compression), the concepts can be used with anysystem for applying external pressure to a body limb. More specifically,the external pressure may be realized through a conventional mechanicaldevice which may include a non-pneumatic mechanical applicator to applynon-pneumatic external pressure to the body limb.

The non-pneumatic mechanical applicator can be configurable to be placedaround at least a portion of the body limb. An example of anon-pneumatic mechanical applicator is a strap which is placed around atleast a portion of the body limb. The strap is then pulled against thebody limb by a mechanical device (such as a motor with gears and/orcams) to as to apply external pressure to the body limb. The mechanicaldevice controls the application of external pressure to the body limb.The external pressure may be intermittent or constant.

The conventional non-pneumatic external pressure device may include astrain gauge or other device to detect a change in a strain beingexperienced by the non-pneumatic mechanical applicator. The detection ofa change in a strain being experienced by the non-pneumatic mechanicalapplicator (detection of the venous phasic flow in the body limb)enables the conventional non-pneumatic external pressure device todetermine a presence of deep vein thrombosis in the body limb.

Although the various embodiments have been described in conjunction witha portable compression system console or small compression systemconsole wherein the source of the pressurized air is within the console,the concepts can be used with any compression system wherein the sourceof pressurized air may be without the console.

For example, it is contemplated that the source of the air pressure forinflation of the pressure sleeves can be located in the patients bed orbe built into the wall of a room. This source of pressurized air can bedirectly connected to the pressure sleeves via proper air conduits(assuming that a pressure control device that regulates or control thedelivery of pressurized air to the pressure sleeves is associated withthe pressurized air source) or can be connected to the pressure sleevesthrough a control device or system that regulates or control thedelivery of pressurized air to the pressure sleeves of the presentinvention.

In other words, a system is contemplated where the source of pressurizedair is integral with the pressure control device or a system where thesource of pressurized air is not integral with the pressure controldevice.

Again as noted above, the concepts have been described with respect touse on a leg of an individual. However, it is to be understood that theconcepts are also extended to use on any body limb such as an arm, afoot, a part of a leg, arm, or foot, and may be used on two or morelimbs simultaneously. Moreover, although the concepts have beendescribed in conjunction with a portable pneumatic compression systemconsole or small pneumatic compression system console wherein the mediumused to provide compression is realized by pressurized air, the conceptscan be used with any compression system wherein the medium used toprovide compression can be realized by a liquid, fluid, gas, or othermechanical means.

While various examples and embodiments have been shown and described, itwill be appreciated by those skilled in the art that the spirit andscope of the embodiments are not limited to the specific description anddrawings herein.

What is claimed is:
 1. A system for diagnosing and preventing, deep veinthrombosis in a body limb, comprising: a compression system for applyingexternal pressure to a body limb; and a venous phasic flow monitoringsystem to monitor a venous phasic flow in a body limb; said venousphasic flow monitoring system determining a presence of deep veinthrombosis in the body limb by detecting a change in a volume of thebody limb.
 2. The system as claimed in claim 1, wherein said compressionsystem includes a non-pneumatic mechanical applicator to applynon-pneumatic external pressure to the body limb, said non-pneumaticmechanical applicator being configurable to be placed around at least aportion of the body limb; said compression system further including amechanical device to cause said non-pneumatic mechanical applicator toapply non-pneumatic external pressure to the body limb.
 3. The system asclaimed in claim 2, wherein said non-pneumatic mechanical applicator isa strap and said mechanical device pulls said strap against the bodylimb to provide non-pneumatic external pressure to the body limb.
 4. Thesystem as claimed in claim 2, wherein said venous phasic flow monitoringsystem determining a presence of deep vein thrombosis in the body limbhaving said non-pneumatic mechanical applicator substantiallytherearound based upon detecting a change in a strain being experiencedby said non-pneumatic mechanical applicator.
 5. The system as claimed inclaim 3, wherein said venous phasic flow monitoring system determining apresence of deep vein thrombosis in the body limb having said strapsubstantially therearound based upon detecting a change in a strainbeing experienced by said strap.
 6. The system as claimed in claim 1,wherein said compression system includes a pressure sleeve to applyexternal pressure to the body limb, the pressure sleeve having afillable cell and being configurable to be placed around a body limb;said compression system further including a source to fill the fillablecell.
 7. The system as claimed in claim 6, wherein said sourcepneumatically fills the fillable cell.
 8. The system as claimed in claim6, wherein said venous phasic flow monitoring system determining apresence of deep vein thrombosis in the body limb having said pressuresleeve therearound based upon detecting a pressure change in saidfillable cell.
 9. The system as claimed in claim 6, wherein saidpressure sleeve includes a plurality of individually fillable cells andsaid source fills each fillable cell individually.
 10. The system asclaimed in claim 9, wherein said source fills a first individuallyfillable cell of said pressure sleeve to a predetermined pressure; saidsource filling a second individually fillable cell of said pressuresleeve while said venous phasic flow monitoring system monitors apressure change in the filled first individually fillable cell of saidpressure sleeve; said venous phasic flow monitoring system determining apresence of deep vein thrombosis in the body limb having said pressuresleeve therearound based upon detecting a pressure change in the filledfirst individually fillable cell of said pressure sleeve.
 11. The systemas claimed in claim 10, wherein said first individually fillable cell ofsaid pressure sleeve is proximal to said second individually tillablecell of said pressure sleeve.
 12. The system as claimed in claim 10,wherein said first individually tillable cell of said pressure sleeve isdistal to said second individually tillable cell of said pressuresleeve.
 13. The system as claimed in claim 11, wherein said venousphasic flow monitoring system determines a presence of deep veinthrombosis in a body limb having said pressure sleeve therearound basedupon increase in baseline pressure being measured by said venous phasicflow monitoring system, the deep vein thrombosis being located proximalto said first individually tillable cell,
 14. The system as claimed inclaim 11, wherein said venous phasic flow monitoring system determines apresence of deep vein thrombosis in a body limb having said pressuresleeve therearound based upon increase in baseline pressure in saidfirst individually tillable cell being measured by said venous phasicflow monitoring system and an obliteration of a detection of venousphasic waves by said first individually tillable cell, the deep veinthrombosis being located proximal to said first individually tillablecell.
 15. The system as claimed in claim 11, wherein said venous phasicflow monitoring system determines a probable deep vein thrombosis islocated in a body limb having said pressure sleeve therearound basedupon substantially no baseline pressure change being measured by saidvenous phasic flow monitoring system, the probable deep vein thrombosisbeing located distal to said first individually fillable and proximal tosaid second individually tillable cell.
 16. The system as claimed inclaim 11, wherein said venous phasic flow monitoring system determines aprobable deep vein thrombosis is located in a body limb having saidpressure sleeve therearound based upon substantially no baselinepressure change being measured by said venous phasic flow monitoringsystem and a detection of venous phasic waves by said first individuallyfillable cell, the probable deep vein thrombosis being located distal tosaid first individually fillable and proximal to said secondindividually fillable cell.
 17. The system as claimed in claim 11,wherein said venous phasic flow monitoring system determines a probableabsence of deep vein thrombosis in a body limb having said pressuresleeve therearound based upon substantially no baseline pressure changebeing measured by said venous phasic flow monitoring system.
 18. Thesystem as claimed in claim 11, wherein said venous phasic flowmonitoring system determines a probable absence of deep vein thrombosisin a body limb having said pressure sleeve therearound based uponsubstantially no baseline pressure change being measured by said venousphasic flow monitoring system and a detection of venous phasic waves bysaid first individually fillable cell.
 19. The system as claimed inclaim 11, wherein said venous phasic flow monitoring system determinespost deep vein thrombosis syndrome in a body limb having said pressuresleeve therearound based upon increase in baseline pressure in saidfirst individually fillable cell being measured by said venous phasicflow monitoring system and a detection of venous phasic waves equal toor greater than normal venous phasic waves by said venous phasic flowmonitoring system, the deep vein thrombosis, causing a partialobstruction, being located proximal to said first individually fillablecell.
 20. The system as claimed in claim 12, wherein said venous phasicflow monitoring system determines a presence of deep vein thrombosis ina body limb having said pressure sleeve therearound based uponsubstantially no pressure change being measured by said venous phasicflow monitoring system, the deep vein thrombosis being located proximalto said second individually fillable cell.